issue515: Audio pitch distortion on TED.com videos

Description:
Whenever I play a video on ted.com, the audio is extremely low
pitched (e.g. it sounds like it's being piped through a voice
changer). I have not experienced this on any other websites I
have tested (e.g. youtube.com, somafm.com), and the behavior is
the same regardless of my selected output device.
Steps to reproduce:
1. Navigate to ted.com.
2. Play a video.
3. Listen for distorted audio.
System Information:
$ lsb_release -a
Distributor ID: Debian
Description: Debian GNU/Linux 9.0 (stretch)
Release: 9.0
Codename: stretch
$ conkeror --version
Conkeror version: conkeror.mozdev.org conkeror 1.0.3 (Debian-1.0.3+git170123-1)
$ pulseaudio --version
pulseaudio 10.0